733667-001-022
AI Summary
This document provides a detailed analysis of the radar data associated with Japan Airlines flight 1628, which reported an unidentified flying object (UFO) during its flight over Alaska on November 17, 1986. The analysis focuses on the phenomenon of uncorrelated radar signals and the normalcy of the radar returns observed during the incident.
Key Findings
- Radar data from JAL flight 1628 on November 17, 1986, showed uncorrelated primary and beacon targets. - FAA experts confirmed that the radar system was functioning normally, despite the pilot's UFO sighting report. - The uncorrelated signals are attributed to timing discrepancies between the primary radar and the aircraft's transponder signals. - Approximately 61 minutes of radar data were analyzed, revealing no abnormalities associated with the reported UFO. - The majority of radar replies were consistent with expected patterns for the region.
OCR Text
REGENERATED RADAR IMAGE OF NOV. 17TH, 1986 JAL #1628, ALASKA PHOTO BY P. STEUCKE, 1-7-87 Regenerated radar data of Nov. 17th, 1986 JAL #1628, Alaska Photo by P. Steucke, 1-7-87 \ Regenerated Radar Data of Nov. 17th, 1986 JAL #1628 Alaska Photo by P. STEUCKE, 1-7-87 \ I \ Regenerated Radar Data of Nov. 17th, 1986 JA~ #1628, Alaska Photo by P. Steucke, 1-7-87 (Distance between dots, bottom of photo is 1/8 to 1/4 mile apart) 1 Paul Steucke F AA Public Affairs 701 C Street, Box 14 Anch. AK 99513 March 5 , 1987 l:JNCORRELATED RADAR SIGNALS Radar data received by the FAA and used to track Japan Airlines flight 1628 on the night of the November 17, 1986, was retained by FAA. Review of this radar data by FAA experts using identical equipment at the FAA's research technical center in Atlantic City, New Jersey, revealed that the radar system w as receiving what is called an "uncorrelated primary and beacon target". This electronic phenomena is not unusual according to Steucke who said, "It is unfortunate that the uncorrelated target phenomena. occurred just when a pilot was reporting seeing something outside his aircraft. The controller's statements, released by the FAA, indicate that they thought t h ere might be another aircraft or object in the area of the JAL flight. Steucke said, "The controllers were doing their job right because they have to work with what is right there in front of them on the screen, especially when you have a Captain that is reporting "other traffic" in his immediate area. The radar data they had was one target, moving slowly across the radar screen. They don't have the benefit of "monday morning quarterbacking" with multiple radar images as was the case in regenerating the radar data." Review of the radar data by FAA experts revealed the "uncorrelated target" phenomena. FAA electronic technicians explained that an "uncorrelated primary and beacon target" on the radar screen occurs when the radar energy that is sent up toward t he aircraft, (primary signal) returns to the radar receiver along with the aircraft transponder (beacon) signal and the two do not match up as being at the same exact location. II II II ) UNCORRELATED RADAR SIGNALS An "uncorrelated primary and beacon(secondary) return on a radar screen occurs when the radar energy that is sent up toward the aircraft (primary signal) returns off the surf ace of the aircraft at a slightly different moment than tbe beacon (secondary) transponder signal and the two do not match up as being at the same place or same computer radar cell. ----------11~--------- --RADAR COMPUTER CELL, 1/4 MILE-- --v'- SECONDARY RADAR RETURN (Beacon) (Transponder) 1/ FAA RADAR Drawing by Paul Steucke March 5, 1987 SAME AIRCRAFT PRIHARY RADAR RETURN (Skin- Surf ace) RADAR CELL =PRIMARY RAD~ RETURN =SECONDARY RADAR RETURN =CORRELATED RETURN (Combined Return) =UNCORRELATED RETURN / Memorandum U.S. Department of Transportation Federal Aviation Administration Subject INFORMATION: Description of Radar Split Image; AAL-5 Meno of 2/5/87 From Manager, Airway Facilities Division, AAL-400 To Public Affairs Officer, AAL-5 Date: Reply to Attn. of : FEB 2 7 1987 'Ihis letter transmits our analysis of the radar targets associated with JAL flight 1628, on November 17, 1986, an::l supplements discussions we have had regardin:J what has been referred to as "split images". We concur with the interpretation provided to you by the Alaskan Region Air Traffic Division. 'Ihe attached Analysis of Uncorrelated Primary an::l Bea.con Targets by Dennis Silllantel covers the subject in m::>re detail, an::l addresses the questions raised in your letter. Paul, I appreciate the team approach you have taken to more fully un::lerstarrl a complex issue. '!he issue is an excellent example of hCM "interdepen::ient" we are. If we can provide any more infonnation, please diliC. David F. Morse Attachment "" --I ::0 ~ .., rn CD ·= ("") __. rn - < ,_ fT1 r-.) CJ ., - J ANALYSIS OF UNCORRELATED PRIMARY AND BEACON TARGETS (JAL-1628, 11/17/86 AKST) Approximately 61 minutes of data was extracted from the EARTS CDR printouts relating to the November 18 incident involving JAL-1628 and the alleged UFO sighting. Review of the data involving this incident did not show any abnormalities that could be associated with any type of target as indicated by the pilot· of JAL-1628. Radar returns from the aircraft and surrounding terrain vary with the different segments of the flight, but are considered normal for the area. Returns relating to the incident can be categorized as three types: primary radar reinforced by a beacon reply (primary radar returns and beacon returns are both evident in the same 1/4 mile range cell), beacon only reply and beacon with an associated radar reply. Seventy-two percent of the replies were radar with beacon reinforcement (same range cel…
Metadata
- Agency
- —
- Classification
- UNCLASSIFIED
- Department
- National Archives and Records Administration
- Catalog source
- View NARA catalog record
NARA Source
- NAID
- 733667
- File
- 733667-001-022.pdf
- Type
- application/pdf
No machine-readable OCR text for this asset. Photographs without captions may have no extractable text.